Rocket propulsion method using iron pentacarbonyl additive



United States Patent "ice 3,150,482 ROCKET PROPULSION METHOD USING IRON PENTACARBONYL ADDHTHVE Jack R. Gould, Monsey, N.Y., assiguor, by mesne assignments, to Thiokoi Chemical Corporation, a corporation of Delaware No Drawing. Filed May 16, E57, Ser. No. 66$,h24 3 Ciaims. ((Ii. 6035.4)

This invention relates to additives for reaction motor fuels, including rocket fuels, and more particularly to means and methods for effecting more rapid and easier ignition, smoother combustion, and improved performance of such fuels.

A principal object of this invention is to provide a material which, when mixed with a hydrocarbon jet fuel, will render the mixture more easily ignitible and more smoothly combustible, with fuming nitric acid as an oxidizer, than is possible with such a fuel-acid system alone.

Other objects and advantages of the invention will appear as the description thereof proceeds.

At the threshold of my description I shall state the respective meanings that I intend to be comprehended in two phrases which will appear hereinafter:

Hydrocarbon Jet Fuel.Such a fuel is contemplated herein to meet US. military specifications (MIL-F- 562413) for high vapor pressure (JP-3) and low vapor pressure (JP-4) grades, when tested in accordance with prescribed methods (VV-L-79l). In some respects the specifications are the same for each of grades JP3 and LIP-4; but vapor pressures are to lie in the range of 5.0 to 7.0 p.s.i. for JP-3, and in the range of 2.0 to 3.0 p.s.i.

for JP-4.

..tion of the ]P4RFNA mixture cannot be initiated successfully with a pyrotechnic squib, in the absence of a primer starting system, such as can be provided by triethyl trithiophosphite (hereinafter ordinarily designated TETP). Even though ignition may be" successful in the presence of such a primer, sustained combustion of the JP-4-RFNA ordinarily cannotbe achieved.

I have discovered that when iron pentacarbonyl (Fe(CO) is mixed in a suitable proportion with a hydrocarbon jet fuel, reliably smooth combustion with RFNA can be effected, after ignition by a powder squib, I

with the aid of the TETP primer. The shutdown characteristics of the propellant combination, containing the iron pentacarbonyl, are good.

The iron pentacarbonyl may be mixed with the hydrocarbon jet fuel in a proportion by weight, relative to the fuel, of about 4 percent to about 11 percent.

An example of the use of iron pentacarbonyl in the practice of my invention is the following:

One part, by weight, of iron pentacarbonyl was mixed with 9 parts of JP-4. The combustion characteristics of this mixture were tested in a -11). thrust rocket engine, using a TETP primer and a pyrotechnic squib for ignition, and RFNA (containing about 18 percent N0 at an O/F ratio of 3.9. A maximum specific impulse of 201 sec. was attained. The shutdown characteristics were good.

The usefulness of iron pentacarbonyl as an additive for a hydrocarbon jet fuel has been demonstrated at O/F ratios in the range from 3.5 to 5.0.

It is to be understood that various modifications and 3 changes in detail in the aforedescribed means and methods may be made without departing from the spirit of my invention; and that all quantities, proportions or ratios stated hereinabove are intended to be illustrative only, and in no sense limitative of the invention other than as the same is defined in the accompanying claims.

What is claimed is:

l. A method of sustaining combustion in a liquid propellant mixture consisting essentially of a liquid hydrocarbon jet fuel and red fuming nitric acid, which method comprises adding between 4 percent and 11 percent by weight of iron pentacarbonyl, said percentage being based on the Weight of liquid hydrocarbon jet fuel.

2. A method of effecting sustained combustion of a liq uid propellant mixture, which method comprises adding 4 percent to 11 percent by weight of iron pentacarbonyl to a mixture consisting essentially of a liquid hydrocarbon jet fuel and red fuming nitric acid, said percentages being based on the weight of'iiquid hydrocarbon jet fuel, and igniting the resulting mixture with a pyrotechnic squib in the presence of a primer of triethyl trithiophosphite.

3. The method of effecting propulsion in a rocket, which method comprises adding from 4 percent to 11 percent by weight of iron pentacarbonyl to a liquid hydrocarbon jet fuel to render said fuel susceptible to sustained combustion in the presence of red fuming nitric acid, then injecting into a rocket combustion chamber a mixture of red fuming nitric acid and said liquid hydrocarbon jet fuel containing iron pentacarbonyl, in proportions such that the ratio of the weight of said nitric acid to the weight of said jet fuel is in the range from about 3.5 to about 5.6, and igniting said mixture of nitric acid and jet fuel by means of a primer of triethyl trithiophosphite and a pyrotechnic squib.

References @ited in the file of this patent Carmody July 10, 1956 

3. THE METHOD OF EFFECTING PROPULSION IN A ROCKET, WHICH METHOD COMPRISES ADDING FROM 4 PERCENT TO 11 PERCENT BY WEIGHT OF IRON PENTACARBONYL TO A LIQUID HYDROCARBON JET FUEL TO RENDER SAID FUEL SUSCEPTIBLE TO SUSTAINED COMBUSTION IN THE PRESENCE OF RED FUMING NITRIC ACID, THEN INJECTING INTO A ROCKET COMBUSTION CHAMBER A MIXTURE OF RED FUMING NITRIC ACID AND SAID LIQUID HYDROCARBON JET FUEL CONTAINING IRON PENTACARBONYL, IN PROPORTIONS SUCH THAT THE RATIO OF THE WEIGHT OF SAID NITRIC ACID TO THE WEIGHT OF SAID JET FUEL IS IN THE RANGE FROM ABOUT 3.5 TO ABOUT 5.0, AND IGNITING SAID MIXTURE OF NITRIC ACID AND JET FUEL BY MEANS OF A PRIMER OF TRIETHYL TRITHIOPHOSPHITE AND A PYROTECHNIC SQUIB. 